![]() ![]() In terms of the history of the characteristic the general outline seems to be that our lineage started out light skinned, lost its fur a few million years ago and developed dark skin, and then diversified in complexion as we spread across the globe. ![]() Not only do older quantitative genetic methods of inquiry come to this conclusion, but new data from genomics confirms this general picture. To review, it seems to be a polygenic trait whose variation world wide tends to be controlled by 4-6 loci of large effect. My pale skinned friend was suitably fried pink despite his protective lotion.I've talked a fair amount about the evolutionary genetics and history of skin color on this weblog. On the flip side a friend of mine who was vacationing in the Maldives told me how he decided to go shirtless on the beach when he saw the locals swaggering about. ![]() It also brought home to me the fact that biology and genetics aren't just theoretical, they're personal. ![]() Now, I do find it interesting that of the few sources for vitamin D fish ranks high, and I do consume more fish than the typical American (who turns down salmon?). Needless to say I'm now taking supplements to bring my nutrition back into its natural balance. But I was obviously fooling myself, my vitamin D levels were half that of the lowest acceptable values. I normally wear sandals, so please note the contrast between my exposed and unexposed skin in terms of pallor. That would fit the bill for my own ecological surroundings for these past few years, but I never believed that I would be susceptible to vitamin D deficiency because I perceived myself as someone who got sufficient sun. The doctor explained to me that this is common amongst darker skinned people who live at high latitudes, especially in areas where cloudiness is the norm. Recently I had some blood work done for a routine check up and it turned out that I had vitamin D deficiency. ![]()
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